The way fruits and vegetables generate new plants is to spread their seeds on the ground. This spreading is accomplished by animals who eat the fruit that has dropped from the tree, bush, or vine. The seeds are eaten and then excreted. From the plants evolutionary point-of-view, creating tasty fruit is the way to keep its flora alive.
While animals don’t mind chomping up the seeds along with the fruit or vegetable, humans are a bit fussier. Some seeds are bitter and hard, like those of grapes. It can be a nuisance biting into a slice of watermelon only to have to pick out the seeds all the time. As a result, horticulturalists have developed many varieties of seedless fruits and vegetables. Sales since the introduction of seedless grapes, navel oranges, and especially watermelons, (the seedless variety was first available commercially in the early 1990s) have soared since their introduction.
Despite their popularity, creating good strains of seedless fruits and vegetables is a long process of careful and tedious cross-breeding. It often takes ten years (or more) to bring a new seedless variety to market.
Of course, creating a new strain of a plant is nothing new. For thousands of years, people have been manipulating plants in order to achieve smaller seeds or bigger fruits. However, it wasn’t until 1856 when the scientist Gregor Mendel, the “father of genetics,” first published his findings about cross-breeding. Mendel’s work showed how specific traits in pea pods turned up in later generations. He theorized that there was a special unit in plants that affected heredity. Despite this enormous intellectual leap, Mendel’s ideas about cross-breeding were not widely implemented until the beginning of the twentieth century. Forty or fifty years later, scientists confirmed that inherited traits are passed down through the genes.
In plants, genes typically are passed down in pairs; these pairs are called an “allele.” In this pair, one gene (usually) is dominant and the other is recessive. Because of this, only the dominant gene is expressed in the biology of the organism, although there remains a second gene for that trait. In every cell’s nucleus are complete genetic maps called “chromosomes.” Chromosomes double when a cell divides and a new copy goes into every cell except for the sex cells (the ovum and sperm). The ovum and sperms carry only half the genetic material, that is, one chromosome from the allele. When ovum and sperm come together, the pair is recombined, and a new individual is created via sexual reproduction. Now there is a complete set of genetic materials, half from the man and half from the woman. When it comes to plant reproduction, a horticulturist tries, to get the most out of trait by breeding plants that has a desired effect, small seeds, perhaps, or easier-to-peel skins on oranges.
It takes many, many years to make a commercially-viable new seedless fruit or vegetable. The reason is that a scientist may have to study thousands of seedlings to find just the right on with the desirable characteristics. Even when they find them, the resulting fruit may not taste very good, or it may be more likely to develop a disease, or it might be misshaped. The “Flame Seedless Grape” for example, came about only after over 10,000 seedlings were experimented upon; it took a total of five different crossings to produce this grape. Seedless watermelons are grown from the sprouting tips of a seedless plant. The tips are put in a petri dish that is filled with nutrients; from one of these petri dishes, one tip can produce an additional fifteen plant-clones. The same is technique is used to create seedless tomatoes.
Despite the long-term development necessary, this area of biotechnology is enormously lucrative and shows no signs of slowing down. In the future, we will likely have many more varieties of seedless vegetables and fruit, and testing-times will likely greatly improve as the science becomes more adept at creating new varietals.
Source: How Products are Made, ©2002 Gale Cengage. All Rights Reserved
The genetics of plants were brought about with Mendel who was the first to publish his work on the genetic transmission of plants. With further experimentation and genetic modification we now have seedless fruits and vegetables! For example the supermarket green seedless grapes are descended from a European seedless grape strain that probably originated between the Black and Caucasus Seas. Grape growers spread this variety all over the world, and the same species exists under many different names.
Gregor Mendel, the father of Plant Biology, was the first to recognize the merits of cross-breeding plants. Seedless fruits and vegetables are the result of evolution or meticulous cross-breeding from farmers. Seedless oranges and grapes however are the result of natural evolution of plants. The seedless orange was result of a seedless orange tree found on a Brazilian Orange Farm as a result of a mutation. Thompson Grapes have been grown in the United States since 1872 and are variants of grapes that are treated with a hormone called gibberillin. The hormone makes sure the grapes grow large and ripe even without the presence of seeds.